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Abstract:

In a communication system, a method and an apparatus provide for
efficient communications of data rate control information. A mobile
station communicates a request on a data channel for reception of a data
file on a traffic channel. In response to the request, a transmitter in
mobile station starts communication of data rate control information on a
data rate control channel. After concluding the delivery of a requested
data file by a receiver in mobile station, transmitter ceases
communication of data rate control information on data rate control
channel from mobile station.

Claims:

1. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: communicate a
request from a mobile station to a base station for delivery of a data
file on a traffic channel from the base station to the mobile station;
communicate data rate control information on a data rate control channel
from the mobile station to the base station; and cease communication of
data rate control information on the data rate control channel from said
mobile station to said base station if the delivery of a data file on a
traffic channel from said base station to said mobile station is
concluded.

2. The non-transitory storage medium of claim 1, wherein communication of
data rate control information on the data rate control channel begins at
a same time as the communicating the request from the mobile station to
the base station for delivery of the data file on the traffic channel.

3. The non-transitory storage medium of claim 1, wherein communication of
data rate control information on the data rate control channel begins
prior to the communicating the request from the mobile station to the
base station for delivery of the data file on the traffic channel.

4. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: communicate
data rate control information on a data rate control channel from a
mobile station to a base station; conclude a delivery of a data file on a
reverse traffic channel from the mobile station to the base station; and
cease, in response to the concluding of the delivery of the data file on
the reverse traffic channel from the mobile station to the base station,
communicating data rate control information on the data rate control
channel from the mobile station to the base station.

5. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: receive data
rate control information via a gate; and control the gate by allowing
transmission of data rate control information, through the gate, during a
busy open state and by ceasing transmission of data rate control
information after transitioning from the busy open state to an idle open
state.

6. The non-transitory storage medium of claim 5, wherein the software
module is firtuer executable to: encode data rate control information to
produce encoded data rate control information; and transmit the encoded
data rate control information to a base station.

7. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: determine a
state of a connection between a mobile station and a base station;
transmit data rate control information from the mobile station to the
base station if the connection state is busy; and cease the transmission
of data rate control information if the connection state transitions from
busy to idle.

8. The non-transitory storage medium of claim 7, wherein the software
module is firtuer executable to: after the transmission has been ceased,
transmit data rate control information from the mobile station to the
base station if the connection state transitions from idle to busy.

9. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: receive data
rate control information via a gate; and control the gate by allowing
transmission of data rate control information, through the gate, during a
busy open state and by ceasing transmission of data rate control
information after transitioning from the busy open state to an idle open
state.

10. The non-transitory storage medium of claim 9, wherein the software
module is furtuer executable to: encode data rate control information to
produce encoded data rate control information; and transmit the encoded
data rate control information to a base station.

11. A non-transitory storage medium having a software module residing
thereon, the software module executable by a processor to: determine a
state of a connection between a mobile station and a base station;
transmit data rate control information from the mobile station to the
base station if the connection state is busy; and cease the transmission
of data rate control information if the connection state transitions from
busy to idle.

12. The non-transitory storage medium of claim 11, wherein the software
module is firtuer executable to: after the transmission has been ceased,
transmit data rate control information from the mobile station to the
base station if the connection state transitions from idle to busy.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present Application for Patent is a continuation of patent
application Ser. No. 11/512,876, filed Aug. 29, 2006, which is a
continuation of patent application Ser. No. 09/965,205, filed Sep. 25,
2001, entitled "Method and Apparatus for Communications of Data Rate
Control Information in a CDMA Communication System" which issued as U.S.
Pat. No. 7,103,021 on Sep. 6, 2005 and assigned to the assignee hereof
and hereby expressly incorporated by reference herein.

BACKGROUND

[0002] I. Field

[0003] The present invention relates generally to the field of
communications, and more particularly, to communications in a cellular
communication system.

[0004] II. Background

[0005] In code division multiple access (CDMA) communication systems,
unnecessary and excessive transmission by a user may cause interference
to other users in addition to reducing the system capacity. The
communication services in a cellular communication system may include
wireless radio transmission of digitized speech, still or moving images,
text messages and other types of data. For providing such services, a
base station may attempt to communicate to a mobile station on a traffic
channel at a data rate that is most recently requested by the mobile
station. The mobile station may make the data rate request on a data rate
control channel. The mobile station may communicate continuously a data
rate control information to the base station in every time slot on the
data rate control channel. The base station, however, at different times
may not have any data for transmission to the mobile station on the
traffic channel. As such, transmission of the data rate control
information on the data rate control channel by the mobile station may be
excessive and unnecessary at different times.

[0006] To this end as well as others, there is a need for a method and
apparatus for efficient communications of the data rate control
information in a communication system.

SUMMARY

[0007] In a code division multiple access communication system, a method
and an apparatus provide for efficient communications of data rate
control information. A mobile station communicates a request on a data
channel for delivery of a data file on a forward link traffic channel. In
response to the request, a transmitter in the mobile station starts a
communication of data rate control information on a data rate control
channel. After concluding the reception of a requested data file by a
receiver in the mobile station, the mobile station transmitter ceases
transmission of the data rate control information on the data rate
control channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The features, objects, and advantages of the present invention will
become more apparent from the detailed description set forth below when
taken in conjunction with the drawings in which like reference characters
identify correspondingly throughout and wherein:

[0009] FIG. 1 illustrates a communication system 100 capable of operating
in accordance with various embodiments of the invention;

[0012] FIG. 4 illustrates a communication system receiver, for operation
in a mobile station and a base station, capable of operating in
accordance with various embodiments of the invention of the invention;

[0013] FIG. 5 illustrates an exemplary timing relationship between a
forward link traffic channel, a data rate control channel and a reverse
link data channel in accordance with various embodiments; and

[0014] FIG. 6 illustrates a block diagram of a transmitter for use in a
mobile station in accordance with various embodiments of the invention.

DETAILED DESCRIPTION

[0015] Various embodiments of the invention may be incorporated in a
wireless communication system operating in accordance with the code
division multiple access (CDMA) technique which has been disclosed and
described in various standards published by the Telecommunication
Industry Association (TIA). Such standards include the TIA/EIA-95
standard, TIA/EIA-IS-2000 standard, IMT-2000 standard and WCDMA standard,
all incorporated by reference herein. A system for communication of data
is also detailed in the "TIA/EIA/IS-856 cdma2000 High Rate Packet Data
Air Interface Specification," incorporated by reference herein, may be
more particularly capable of incorporating various embodiments of the
invention. A copy of the standards may be obtained by accessing the world
wide web at the address: http://www.3gpp2.org, or by writing to TIA,
Standards and Technology Department, 2500 Wilson Boulevard, Arlington,
Va. 22201, United States of America. The standard generally identified as
WCDMA standard may be obtained by contacting 3GPP Support Office, 650
Route des Lucioles-Sophia Antipolis, Valbonne-France.

[0016] Generally stated, a novel and improved method and an accompanying
apparatus provide for an effective communications of the data rate
control information in a CDMA communication system. One or more exemplary
embodiments described herein are set forth in the context of a digital
wireless data communication system. While use within this context is
advantageous, different embodiments of the invention may be incorporated
in different environments or configurations. In general, the various
systems described herein may be formed using software-controlled
processors, integrated circuits, or discrete logic. The data,
instructions, commands, information, signals, symbols, and chips that may
be referenced throughout the application are advantageously represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or a combination thereof. In
addition, the blocks shown in each block diagram may represent hardware
or method steps.

[0017] FIG. 1 illustrates a general block diagram of a communication
system 100 capable of operating in accordance with any of the code
division multiple access (CDMA) communication system standards while
incorporating various embodiments of the invention. Communication system
100 may be for communications of voice, data or both. Generally,
communication system 100 includes a base station 101 that provides
communication links between a number of mobile stations, such as mobile
stations 102-104, and between mobile stations 102-104 and a public switch
telephone and data network 105. The mobile stations in FIG. 1 may be
referred to as the data access terminals and the base station as the data
access network without departing from the main scope and various
advantages of the invention. The access terminals may be portable or
stationary computers.

[0018] Base station 101 may include a number of components, such as a base
station controller and a radio frequency transceiver. For simplicity,
such components are not shown. Base station 101 may also be in
communication with other base stations, for example base station 160. A
controller (not shown) may control various operating aspects of the
communication system 100 and particularly in relation to a backhaul 199
between network 105 and base stations 101 and 160.

[0019] Base station 101 communicates with each mobile station in a
coverage area via a forward link signal transmitted from base station
101. The forward link signals targeted for mobile stations 102-104 may be
summed to form a forward link signal 106. Each of the mobile stations
102-104 receiving forward link signal 106 decodes the forward link signal
106 to extract the information targeted for its user. Base station 160
may also communicate with the mobile stations 102-104 via a forward link
signal transmitted from base station 160. Mobile stations 102-104
communicate with base stations 101 and 160 via corresponding reverse
links. Each reverse link is maintained by a reverse link signal, such as
reverse link signals 107-109 for respectively mobile stations 102-104.

[0020] In a soft handoff situation, base stations 101 and 160 may be
communicating to a common mobile station in an overlapping coverage area.
For example, mobile station 102 may be in the overlapping coverage area
of base stations 101 and 160. Therefore, mobile station 102 may maintain
communications with both base stations 101 and 160. On the forward link,
base station 101 and 160 transmit respectively on forward link signals
106 and 161. On the reverse link, mobile station 102 transmits on reverse
link signal 107 to be received by both base stations 101 and 160. For
transmitting a data unit to mobile station 102 in soft handoff, mobile
station 102 may select one of the base stations to be a serving base
station for transmitting the data unit. The non-serving base station does
not transmit the data unit on the forward link. On the reverse link, both
base stations 101 and 160 may attempt to decode the traffic data
transmission from the mobile station 102.

[0021] FIG. 2 illustrates a forward channel structure 200 in accordance
with an embodiment that may be used for communications on the forward
link. Forward channel structure 200 may include a pilot channel 201, a
medium access control (MAC) channel 202, a traffic channel 203 and a
control channel 204. MAC channel 202 may include a reverse activity
channel 206 and a reverse power control channel 207. Reverse activity
channel 206 is used to indicate the activity level on the reverse link.
Reverse power control channel 207 is used to control the power at which a
mobile station can transmit on the reverse link.

[0022] FIG. 3 illustrates, in accordance with an embodiment, a reverse
channel structure 300 that may be used for communications on the reverse
link. Reverse channel structure 300 includes an access channel 350 and a
traffic channel 301. Access channel 350 includes a pilot channel 351 and
a data channel 353. Traffic channel 301 includes a pilot channel 304, a
MAC channel 303, an acknowledgment (ACK) channel 340 and a data channel
302. MAC channel 303 includes a reverse link data rate indicator channel
306 and a data rate control channel (DRC) 305. Reverse rate indicator
channel 306 is used for indicating the rate at which a mobile station is
currently transmitting. Data rate control channel 305 indicates a data
rate that a mobile station is capable of receiving at a time on the
forward link. ACK channel 340 is used for communicating after receiving
each data unit whether a packet of data has been decoded successfully at
a mobile station.

[0023] Data channel 302 may be used by a mobile station to communicate
traffic data to the base station. For example, traffic data may include a
request for receiving a data file on the forward link. Traffic data may
also include commands and inputs from the mobile station user made via an
interaction with the mobile station. The interaction may be via the
mobile station keypad, display or voice command. For packet data
application, the communications on the forward link traffic channel 203
is typically initiated in response to a communication on the reverse link
data channel 302.

[0024] FIG. 4 illustrates a block diagram of a receiver 400 used for
processing and demodulating a received CDMA signal. Receiver 400 may be
used for decoding the information on reverse and forward links signals.
Receive samples may be stored in RAM 404. Receive samples are generated
by a radio frequency/intermediate frequency (RF/IF) system 490 and an
antenna system 492. Antenna system 492 receives an RF signal, and passes
the RF signal to RF/IF system 490. RF/IF system 490 may be any
conventional RF/IF receiver. The received RF signals are filtered,
down-converted and digitized to form the received samples at the base
band frequencies. The samples are supplied to a demultiplexer (demux)
402. The output of demux 402 is supplied to a searcher unit 406 and
finger elements 408. A control unit 410 is coupled thereto. A combiner
412 couples a decoder 414 to finger elements 408. Control unit 410 may be
a microprocessor controlled by software, and may be located on the same
integrated circuit or on a separate integrated circuit. The decoding
function in decoder 414 may be in accordance with Viterbi algorithm or a
turbo decoding algorithm.

[0025] During operation, receive samples are supplied to demux 402. Demux
402 supplies the samples to searcher unit 206 and finger elements 408.
Control unit 410 configures finger elements 408 to perform demodulation
of the received signal at different time offsets based on search results
from searcher unit 406. The results of the demodulation are combined and
passed to decoder 414. Decoder 414 decodes the received data symbols and
outputs the decoded data symbols. Despreading of the channels is
performed by multiplying the received samples with the complex conjugate
of the PN sequence and assigned Walsh function at a single timing
hypothesis and digitally filtering the resulting samples, often with an
integrate and dump accumulator circuit (not shown). Such a technique is
commonly known in the art.

[0026] The states of a data connection between a mobile station and a base
station upon a successful connection setup may include a busy open state
and an idle open state. When a connection is in a busy open state, the
base station and the mobile station may exchange traffic data. The
traffic data may originate from either the base station or the mobile
station. Forward traffic channel 203 and data channel 302 may be used. In
the idle open state, the base station and the mobile station may not
exchange traffic data packet. Traffic data may not be exchanged for
different reasons including the completion of delivery of a previously
requested data file. When there is no traffic data to be exchanged, the
state of the connection transitions from the busy open state to the idle
open state. In the idle open state, the connection setup is not torn
down; i.e. a link is available for possible data delivery. When traffic
data becomes available for transmission from either the base station or
the mobile station, the state of the connection transitions from the idle
open state to the busy open state.

[0027] The base station may use the latest communicated data rate control
information to transmit traffic data to the mobile station on the forward
link traffic channel 203. During idle and busy open states, the mobile
station may transmit data rate control information on DRC 305 to the base
station. During busy open state, data rate control information is used
for setting the data rate of the traffic data transmitted during the
following time slots on the forward link traffic channel 203. During idle
open state, the communications on DRC 305 is unnecessary because the
forward link traffic channel 203 is not used for transmission of traffic
data to the mobile station. When the state of the connection transitions
from the idle open state to the busy open state, the data rate control
information communicated on DRC 305 may become useful. Therefore,
communications on DRC 305 during idle open state connection is
unnecessary and excessive.

[0028] Referring to FIG. 5, an exemplary timing relationship between
forward traffic channel 203 transmitted from a base station, DRC 305 and
reverse data channel 302 transmitted from a mobile station is shown. The
mobile station and the base station may have a data connection. During a
time period 501, the data connection may be in the busy open state. The
base station on the forward traffic channel 203 transmits data to the
mobile station during busy open state time period 501. The data may be
transmitted during several time slots. The mobile station transmits on
the reverse link data rate control information on DRC channel 305 during
the busy open state time period 501. The busy open state time period 501
may be preceded by at least a communication on the reverse data channel
302 on a time slot prior to time slot "n." The time slot may be a time
slot "n-1." The data carried by the reverse data channel 302 during time
slot "n-1," or any other time slot preceding time slot "n," may be, for
example, a request for receiving a data file on the forward traffic
channel 203 during the busy open state time period 501. The forward
traffic channel 203 may begin transmitting data at the time slot "n." The
delivery of the data file may be completed at the time slot "n+k."

[0029] After completing the delivery of the data file on the forward
traffic channel 203 to the mobile station, and when the mobile station
does not expect to receive any other files, including ACK or NAK of
previously transmitted data packets, on the forward traffic channel 203,
the mobile station may terminate transmission of data rate control
information on the DRC 305, in accordance with various embodiments of the
invention. Transmission of data rate control information on DRC 305 may
begin at the same time or just prior to a request by the mobile station
on the reverse data channel 302 for delivery of a data file on the
forward traffic channel 203. Transmission of data rate control
information on DRC 305 may alternatively begin at the same time or just
prior to a start time of the busy open state time period 501. The mobile
station may need to have an information about the start time of the busy
open state time period 501. Transmission of data rate control information
on DRC 305 may alternatively begin at the same time or just prior to a
start time of the delivery of a data file on the reverse data channel
302. The mobile station may need to have an information about the
delivery time.

[0030] The idle open state connection period may be the period between the
termination of delivery of a data file on the forward traffic channel 203
and the start of a next delivery of a data file on the forward traffic
channel 203. Such a time period is shown as a time period 502. At the end
of time period 502 or near the end of time period 502, the mobile station
may request for delivery of data. A request for deliver of data on data
channel 302 may terminate the idle open state 502. The transmission of
data rate control information on DRC 305 may begin nearly at the same
time as the termination time of the idle open state time period 502, in
accordance with various embodiments of the invention. Transmission on DRC
305 may begin, for example, at the time slot "m-1," as shown in FIG. 5.
The transmission on DRC 305 may alternatively begin at the same time as
the transmission of the request for a data file on the reverse data
channel 302.

[0031] Referring to FIG. 6, a block diagram of a transmitter 600 in
accordance with various embodiments for use in a mobile station is shown.
Various data from different channels input a pre-transmit processing
block 670 to produce I and Q signals 671 and 672. Signals 671 and 672 are
summed in a summer 673. The summed signal is amplified in an amplifier
674. The amplified signal is transmitted from an antenna 675 to the base
station.

[0032] An encoder 612 encodes data for transmission, for example, on data
channel 302. The encoded data passes through a block interleaver 614. The
interleaved data is Walsh covered in a multiplier 616. The Walsh covered
output passes through a channel gain adjustment in block 618 for in-phase
and quadrature (I&Q) modulations in multipliers 650A-D. The ACK/NAK
information for transmission on ACK channel 340 passes through level
adjustments in block 698. The output data may be repeated in block 697,
and Walsh covered in multiplier 696. The output passes through a gain
adjustment block 695. A summer 694 may sum the data on the ACK channel
340, the pilot data on pilot channel 304 and the data on DRC 305.

[0033] An encoder 626 encodes the data rate control information for
transmission on DRC 305. The encoded data is Walsh covered in a
multiplier 628. In accordance with various embodiments, the data rate
control information may be gated by a DRC block 676. A DRC gate
controller 677, in accordance with various embodiments, may control the
operations of the DRC gate block 676. The DRC gate block 676, for gating
transmission on DRC 305, may be placed at different locations along the
DRC 305 modulation path. The DRC gate block 676 may be placed after the
Walsh covered operation. The Walsh covered data rate information may be
ready for an immediate transmission after DRC gate controller 677 enables
the transmission. In accordance with various embodiments, the
transmission of data rate control information may cease after termination
of the busy open state time period 501, and resume before or about the
same time as the start of the next busy open state period.

[0034] The DRC gate controller 677 may trigger the resumption of
transmission on DRC 305 based on availability of data for transmission on
data channel 302, in accordance with an embodiment. Encoder 612 may
receive the data for transmission on data channel 302. After completing
the delivery of the data file on the forward traffic channel 203 to the
mobile station, and when the mobile station does not expect to receive
any other files on the forward traffic channel 203, DRC gate controller
677 may terminate transmission of data rate control information on the
DRC 305, in accordance with an embodiment. DRC gate controller 677 may
allow transmission of data rate control information on DRC 305 at the
same time or just prior to a request by the mobile station on the reverse
data channel 302 for delivery of a data file on the forward traffic
channel 203, in accordance with an embodiment. DRC gate controller 677
may allow transmission of data rate control information on DRC 305 to
alternatively begin at the same time or just prior to a start time of the
busy open state time period 501, in accordance with an embodiment. The
mobile station may need to have an information about the start time of
the busy open state time period 501. DRC gate controller 677 may allow
transmission of data rate control information on DRC 305 to alternatively
begin at the same time or just prior to a start time of the delivery of a
data file on the reverse data channel 302, in accordance with an
embodiment. The mobile station may need to have an information about the
delivery time.

[0035] At the end of time period 502 or near the end of time period 502,
the mobile station may request for delivery of data by transmitting some
data on data channel 302. DRC gate controller 677 may allow the
transmission of data rate control information on DRC 305 to begin nearly
at the same time as the termination time of the idle open state time
period 502, in accordance with various embodiments of the invention. DRC
gate controller 677 may allow transmission on DRC 305 to begin, for
example, at the time slot "m-1," as shown in FIG. 5. DRC gate controller
677 may allow the transmission on DRC 305 to alternatively begin at the
same time as the transmission of the request for a data file on the
reverse data channel 302, in accordance with an embodiment.

[0036] The encoded data from DRC 305, ACK channel 340 and data channel
302, and pilot data on channel 304 may pass through I&Q modulator 650A-D,
filters 652A-D and summers 654A-B as shown to produce I and Q signals 671
and 672 for transmission.

[0037] Those of skill in the art would further appreciate that the various
illustrative logical blocks, modules, circuits, and algorithm steps
described in connection with the embodiments disclosed herein may be
implemented as electronic hardware, computer software, or combinations of
both. To clearly illustrate this interchangeability of hardware and
software, various illustrative components, blocks, modules, circuits, and
steps have been described above generally in terms of their
functionality. Whether such functionality is implemented as hardware or
software depends upon the particular application and design constraints
imposed on the overall system. Skilled artisans may implement the
described functionality in varying ways for each particular application,
but such implementation decisions should not be interpreted as causing a
departure from the scope of the present invention.

[0038] The various illustrative logical blocks, modules, and circuits
described in connection with the embodiments disclosed herein may be
implemented or performed with a general purpose processor, a digital
signal processor (DSP), an application specific integrated circuit
(ASIC), a field programmable gate array (FPGA) or other programmable
logic device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the functions
described herein. A general purpose processor may be a microprocessor,
but in the alternative, the processor may be any conventional processor,
controller, microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices, e.g., a combination of
a DSP and a microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration.

[0039] The steps of a method or algorithm described in connection with the
embodiments disclosed herein may be embodied directly in hardware, in a
software module executed by a processor, or in a combination. A software
module may reside in RAM memory, flash memory, ROM memory, EPROM memory,
EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any
other form of storage medium known in the art. An exemplary storage
medium is coupled to the processor such that the processor can read
information from, and write information to, the storage medium. In the
alternative, the storage medium may be integral to the processor. The
processor and the storage medium may reside in an ASIC. The ASIC may
reside in a user terminal. In the alternative, the processor and the
storage medium may reside as discrete components in a user terminal.

[0040] The previous description of the preferred embodiments is provided
to enable any person skilled in the art to make or use the present
invention. The various modifications to these embodiments will be readily
apparent to those skilled in the art, and the generic principles defined
herein may be applied to other embodiments without the use of the
inventive faculty. Thus, the present invention is not intended to be
limited to the embodiments shown herein but is to be accorded the widest
scope consistent with the principles and novel features disclosed herein.